2D 3D perovskite engineering eliminates interfacial recombination losses in hybrid perovskite solar cells

Interface engineering and design is paramount in the optimization of a multilayer device stack. This stands true for multi dimensional 2D 3D perovskite based solar cells, in which high efficiency can be combined with promising device durability. However, the complex function of the 2D 3D device interfaces remains vague. Here, we provide the exact knowledge on the interface energetics and demonstrate that the 2D 3D perovskite interface forms a p n junction that is capable of reducing the electron density at the hole transport layer interface and ultimately suppresses interfacial recombination. As a consequence, we demonstrate photovoltaic devices with an enhanced fill factor FF and open circuit voltage V OC of 1.19 V, which approaches the potential internal quasi Fermi level splitting QFLS voltage of the perovskite absorber, nullifying the interfacial losses. We thus identify the essential parameters and energetic alignment scenario required for 2D 3D perovskite systems to surpass the current limitations of hybrid perovskite solar cell performance